This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To identify peptides that modulate ingestive behavior in primates. Obesity has reached epidemic proportions in developed countries and this is having a profoundly negative impact on health and health care systems. Several peptides have recently been identified that may regulate appetite and feeding behaviors. We have been evaluating the effects of central and peripheral administration of these substances and their antagonists in rhesus monkeys, with the long-term aim of reducing obesity and ameliorating its consequences. In an effort to enhance the model we are using to study obesity, we developed and tested a fat-enriched maintenance diet. The diet was found to be highly palatable to rhesus monkeys and effective in increasing caloric intake. This research used WNPRC Animal Services and Aging Resources. The work provided the basis for a Master of Science degree for a student in the Department of Nutritional Sciences.